Mold purging apparatus and method



United States I Patent 3,265,348 MOLD PURGING APPARATUS AND METHODEdmund Q. Sylvester, Shaker Heights, Ohio Filed Nov. 23, 1964, Ser. No.413,132 7 Claims. (Cl. 249109) The present invention relates toapparatus and method for purging molds of air and any other gases by theintroduction of an inert gas into the mold and consequent displacementofthe air and other gases.

A broad object of the invention is to provide novel apparatus and methodfor introducing the inert gas, which may be argon, into the mold. Theargon is heavier than air and when the mold is purged of air and othergases by argon, the argon remains in the mold against any tendency todisplace it by other gases.

One difiiculty that has been encountered heretofore in purging molds byinert gas such as argon is that upon introduction of the argon aturbulence is created and the argon mixes with the air, and aninefiicient purging operation resulted.

Another object of the present invention is to provide means and methodfor introducing a purging gas into a mold in such a way that it flows atthe same rate in all portions of the mold and thereby substantiallyeliminates turbulence, resulting in a highly efficient purgingoperation.

A still further object is to provide novel apparatus and method forpurging a mold by the introduction of a purging gas at the bottomthereof and which provides for effectively closing the bottom openingthrough which the purging gas is introduced but which enables effectiveintroduction of molten metal to be cast through that bottom openingwithout losing any of the purging gas therethrough.

More specifically an object is to provide apparatus and method of thecharacter just mentioned wherein a disintegrateable closure member isutilized for closing the bottom opening in the mold means, the moldmeans having a passage therethrough for introducing purging gas throughthe bottom opening, the closure member yielding for enabling this step,and the closure member disintegrating in the operation of bottom pouringinto the mold.

Other objects and advantages of the invention will appear from thefollowing detailed description taken in conjunction with theaccompanying drawing in which:

FIGURE 1 is a vertical sectional view through apparatus made accordingto the present invention; and

FIGURE 2 is a small scale view of the components of FIGURE 1, partiallyin elevation and partially in section, in partially separated position.

Referring now in detail to the drawings the apparatus shown includes aningate construction indicated generally at 12, a mold 14, thereabove anda pressure pouring tube 16 in pouring relation to the ingateconstruction. The mold 14 and the pouring tube 16 may be of conventionalconstruction and the features of the present invention are incorporatedin the ingate construction 12.

The mold 14 includes a body made up of a plurality of blocks 18 whichmay be of graphite and which define a casting cavity 20. The pouringtube 16 includes a shank 22 and a head 24 having a tapered upper surface26 adapted for engagement with a corresponding element of the ingateconstruction 12. The pouring tube 16 includes a liner 28 preferably ofceramic material which defines an annular pouring passage 30. As will beunderstood, the pouring tube 16 is utilized with a ladle in anarrangement in which superatmospheric pressure is applied to the ladlewhich forces molten metal therein upwardly through the pouring tube,through the ingate construction 12 and into the cavity of the mold.

Reference is now madeto the ingate construction 12. This ingateconstruction is provided with a vertical passage 32 for the passage ofmolten metal therethrough, which in the assembly with the mold andpouring tube registers and communicates with the passage 30 in thepouring tube and the cavity 20 in the mold. The ingate constructionincludes a number of members which may be conventional and found inother ingate constructions heretofore known; it includes a chill block34 which may be of metal and which directly supports the mold 14 andfunctions to increase the cooling rate of the mold.

The chill block 34 is provided with a central aperture 35 in which aceramic liner 36 is disposed defining a portion of the passage 32. -Nextbelow the chill block 34 is a slide 38 guided by guide bars on oppositesides thereof, the arrangement being that the slide may be operated fromthe exterior for movement between open position (shown in the drawings)and closed position. This slide arrangement is conventional and it isbelieved unnecessary to show additional details thereof. It is movedbetween open and closed positions in directions perpendicular to thepaper. The slide 38 is provided with an aperture 41 also having aceramic liner 42 which defines another portion of the passage 32. Themovement of the slide is suificient to move the aperture thereinentirely out of registration with the remainder of the passage. Nextbelow the slide is a gate assembly piece 44 having an aperture 45,in'which is disposed a ceramic liner 46 defining a third portion of thepassage 32.

The foregoing members of the ingate construction are together supportedby the lowermost member which is the spout receptacle 48, all of themembers of the ingate construction being suitably secured together in arigid assembly by suitable conventional means.

The spout receptacle 4-8 includes a main plate like portion 50 dependingfrom which is an annular extension 52 which defines a recess 54 having atapered surrounding wall 55 and an annular top surface 57 which alsoconstitutes a bottom surface of the spout receptacle. recess 54 receivesthe head 24 of the pouring tube and the surface 55 engages the surface26 thereof.

The spout receptacle 48 is provided with an aperture 58 in which isdisposed another ceramic liner 59 defining the fourth and lowermostportion of the passage 32. The spout receptacle 48 is provided with aradial bore 59' at the outer end of which is suitably connected a line60 leading from a source of the purging gas such as argon. Preferablythis line 60 is provided with a quick disconnect arrangement 62. Thebore 59 leads into a downwardly directed bore 64 which opens through thesurface 57 of the recess 54. The surface 57 is counterbored at 68 ofsuch radial dimension :as to extend into the vertical bore 64.Positioned in this counterbore 68 is an annular ring 70 secured theretoby suitable means such as screws 72. This ring terminates outwardly at74 in line with the radially inner surface 76 of the vertical bore 64 soas to leave an annular passage 78 which communicates with the verticalbore 64 and provides an annular passage completely around the recess 54and opening downwardly through the surface 57.

Secured to the surface 57 is a member for closing the lower end of thepassage 32 and thus closing the mold. This member is in the form of adiaphragm 80 which may be paper or other quickly disintegrateablematerial. The diaphragm is held in place by a snap ring 82 yieldinglyheld in a circumferential groove 84 formed in the upper extremity of thetapered surface 55. The margin-al edge of the diaphragm is placed in thegroove and the snap ring snapped in place thereover to hold thediaphragm in place. An annular gasket 86, which may be of asbestos, issecured to the diaphragm as by cementmg.

The

In the practical operation of the apparatus the argon under suitablepressure is introduced through the line 60 and bore 59'. It flowsdownwardly through the bore 64 and into the annular passage 78, and thenworks against the diaphragm and flexes it downwardly (includingthegasket 86) to the dotted line position of FIGURE 2, providing acomplete circular space establishing communication with the passage 32.The argon forces the air and all other gases ahead of it and forms acolumn of pure argon in the passage 32 pushing the gases upwardly. Inkeeping with a principal advantage of the invention the argon isintroduced at a rate sufiiciently low to prevent turbulence with theair. One of the features working to this end is the introduction of theargon from all directions to the passage 32, i.e., in the space directlyabove the diaphragm when the diaphragm is fixed downward. The flow ofargon is continued in such rate as to continuously maintain a column ofpure argon which forces the air and all other gases out of the mold.

In the step of introducing the argon the ingate construction 12 iseither removed from the pouring tube, or spaced upwardly therefrom(FIGURE 2) a sufficient distance to enable the diaphragm to be flexeddownwardly and after the purging step has been completed the ingateconstruction with the mold is lowered, or if desired the pouring tuberaised, to establish proper pouring engagement. In addition to theengagement of the tapered surface 55 with the pouring tube head, thegasket 86 provides additional sealing engagement between the surface ofthe recess and the pouring tube.

Upon the molten metal, such as steel, rising in the pouring tube itengages the diaphragm and disintegrates it. In the case of paper thepaper is burned. However, the diaphragm maybe made of any of variousmaterials, for example, aluminum foil which is readily and quicklymelted by the molten metal.

While I have disclosed herein a certain preferred form of the invention,it will be understood that changes may be made therein within the scopeof the appended claims.

I claim:

1. Mold means having a bottom pouring opening, a bottom surface throughwhich said pouring opening opens, a purging gas passage for introducinginert gas into said mold, saidpassage opening through said bottomsurfaceadjacent .to but offset from said bottom pouring opening, and means forclosing said bottom pouring opening, said closing means disintegrateableby material poured into the mold for cast-ing and being secured to saidbot-tom surface in covering relation to both the pouring opening andsaid purging gas passage and is enabled to yield and spread from saidbottom surface in response to gas introduced through said purging gaspassage whereby to form an open space between the closing means and saidbottom surf-ace establishing communication between said purging gaspassage and pouring opening.

2. The invention set out in claim 1 wherein said botto surface includesan annular groove therein communicating with said purging gas passageforming an extension thereof opening through said bottom surface wherebywhen the closing means is separated from said bottom surface, gas isenabled to flow from said purging gas passage into said space radiallyinwardly in all directions.

3. The invention set out in claim 2 in which the closing means isburnable.

4. Mold means adapted for use in bottom pressure pouring castingcomprising a mold having a downwardly opening cavity, ingateconstruction below and supporting the mold and having a pouring passagetherethrough in register with and communicating with the cavity, thepassage opening downwardly through the, ingate construction and theingate construction including a spout receptacle as a lowermost elementhaving a recess including a surface in its upper portion defining abottom surface of the ingate construction and surrounding said passage,the spout receptacle also including a downwardly extending annularprojection defining -a downwardly and outwardly tapering surroundingwall of the recess, the ingate construction having a radially inwardlyextending purging gas passage opening downwardly through said annularbottom surface adjacent to but spaced from said pouring passage, and adisintegrateable diaphragm covering said bottom surface and coveringsaid pouring passage and purging gas passage, means releaseably securingthe marginal edge of the diaphrgam to said downwardly tapering walladjacent said bottom surface, said diaphragm being yieldable in responseto introduction of inert gas under pressure through said purging gaspassage whereby to provide a space between itself and said bottomsurface continuous from the purging gas passage to the pouring passage.

5. The invention set out in claim 4 wherein an annular gasket is securedto said diaphragm in surrounding relationship'to said pouring passageand effective for establishing sealing relation between an upper surfaceof a vertical pouring tube and said bottom surface when said pouringtube is introduced into said recess.

6. A method of casting in conjunction with mold means having a cavityand a downwardly opening passage communicating with the cavity,comprising closing the bottom open end of the passage with adisintegrateable closure, introducing inert gas into said passage fromthe bottom of the passage above said closure and continuing theintroduction of the inert gas sufficiently to fill the passage andcavity and at a rate of flow sufliiciently low to eliminate turbulenceand mixture between the inert gas and air, and pouring molten castingmaterial into the mold by pouring it against the disintegrateableclosure and thereby disintegrating it, and continuing the pouring stepuntil the mold is filled.

7. The invention set out in claim 6 wherein the inert gas is introducedinto the passage by directing it into that passage radially inwardly inall directions.

References Cited by the Examiner UNITED STATES PATENTS 674,341 5/1901Lustig 22-214 2,082,588 6/ 1937 Menetry 22-69 2,521,362 9/1950 Grausan222l4 2,912,728 11/1959 Sylvester 2269 3,142,099 7/1964 Burch 22-2143,163,897 1/ 1965 Sylvester 22-69 J. SPENCER OVERHOLSER, PrimaryExaminer. MARCUS U. LYONS, Examiner.

6. A METHOD OF CASTING IN CONJUNCTION WITH MOLD MEANS HAVING A CAVITYAND A DOWNWARDLY OPENING PASSAGE COMMUNICATING WITH THE CAVITY,COMPRISING CLOSING THE BOTTOM OPEN END OF THE PASSAGE WITH ADISINTEGRATEABLE CLOSURE, INTRODUCING INERT GAS INTO SAID PASSAGE FROMTHE BOTTOM OF THE PASSAGE ABOVE SAID CLOSURE AND CONTINUING THEINTRODUCTION OF THE INERT GAS SUFFICIENTLY TO FILL THE PASSAGE ANDCAVITY AND AT A RATE OF FLOW SUFFICIENTLY LOW TO ELIMINATE TURBULENCEAND MIXTURE BETWEEN THE INERT GAS AND AIR, AND POURING MOLTEN CASTINGMATERIAL INTO THE MOLD BY POURING IT AGAINST THE DISINTEGRATEABLECLOSURE AND THEREBY DISINTEGRATING IT, AND CONTINUING THE POURING STEPUNTIL THE MOLD IS FILLED.